Prepare and roll out pastry for a single-crust pie. Fit the pastry into a 9-inch pie plate, trimming and crimping the edges as desired.
Line the unbaked crust with a double thickness of foil and bake at 450°F for 8 minutes. Carefully remove the foil and continue baking for an additional 4–5 minutes, or until the crust is set and lightly dry.
Remove from the oven and reduce the oven temperature to 325°F.
In a large skillet, cook the onion and bacon together until the onion is soft and the bacon is crisp. Drain the mixture on paper towels to remove excess grease.
In a large bowl, whisk together the eggs, sour cream, and half-and-half until smooth. Season with salt, pepper, and nutmeg.
Stir in the cooked onion and bacon mixture, followed by the broccoli and cheddar cheese. Mix until everything is evenly combined.
Pour the filling into the prepared pie crust.
Bake for about 55 minutes, or until the center is set and the top is lightly golden.
Let cool slightly before serving.